Refrigerating system and method



J. c. GOQSMANN REFRIGERATING SYSTEM AND 'METH'OD May 9 Filed O61'.

NEU

Patented May 9, 193.?.l

UNITED STATES'HP'AT n f 1,908,290v

ENT OFFICE:

JUSTUS C.` GOOSMANN, OF CHICAGO, ILLINOIS BEFBIGERATING- SYSTIEIJIBIyMETHOD Application led October 1.3, 1930. Serial No. 488202.'

This invention relates in general to refrigeratings stems'andmeth'ods.

One o the objectsof the invention is to provide a refrigerating systemand method employing carbon dioxide refrigerant in its solid, liquid,and gaseous phases. A

Another v object of this invention is the provision of apparatus andmethods by means of which solid carbon dioxide may be employed to douseful refrigerating .work by heat exchange between the solid CO2 andthe space or the medium to be refrigerated.

Another object of this invention is the provision of apparatus andmethods by means of. which maximum economy may be elect-ed in utilizingsolid carbon dioxide for refrigerating purposes.

Astill further object of this invention is the provision of meanswhereby a complete heat exchange between the solid CO2 refrig-l erantandthe medium to be refrigerated isv effected, together with theapplication of eX- ternal' heat which is automatically introduced whennecessary to make the heat exchange cycle complete and automaticallyop-v erative. Y

Another object of "this invention is the provision of relatively low andmoderately high temperature refrigerating cabinets with carbon dioxidegas and liquidl coils connected together for the purpose of utilizingsolid carbon dioxide for refrigerating purposes, together with means forchanging the state of the medium in the cycle.

A still further object of this invention is the provision of asystemfrom which the carbon dioxide gas may be withdrawn after doinguseful refrigerating work-for such other purposes as may be available,such as., for liquid carbonating purposes.

These and many other objects as will` appear from thefollowingidisclosure are secured by means of the apparatus and methodsof this invention. l

This invention resides substantially in the combination, construction,arrangement, relative locationof parts, steps and series of steps, -allas will be explained in greater detail in the following specication Theaccompanying drawing is a'diagrammatic view with some parts in crosssection of the apparatus of this invention.

The general object of this inventionisto provide apparatus and methodsby means of which the cooling properties of solid carbon dioxide may beutilized to the maximum extent in doing useful refrigerating Work. Ingeneral the system comprises a container forz the solidcarbon dioxide soproportioned with' respect to the volume of solid CO2 placed 60 thereinthat the gas generated therefrom will be liquefied in a primarycondenser coil 10- cated at the bottom ofof the container by thecombined action of the built-up pressure in the container and thecooling work of thesolid COZ in close proximity with the said primarycondenser coil. The liqueiiedl car# bon dioxide is then passed into arefrigerating chamber and circulated through the liquid coil, deliveredto a gas coil, and there permitted to vaporize. This vaporization oflthe liquid is caused by absorption of vheat fromthe refrigeratingchamberthereby cooling it.' Means is provided between the liquid and gas coilsfor insuring that liquid Idelivered to the ygas coils may vaporizetherein. This vapor is then circulated in heat exchange relation withthe container holding the solid carbon dioxide through a secondarycondenser coil whereby it is cooled and gives up heat to effect furthervaporization or sublimation of the solid'carbon dioxide. The liquid, or.a mixture of liquid and vapor, is then -circu- .l lated through anotherrefrigerating space which is maintained at refrigerating tem- 8 5peratures that are higher than those in the first refrigerator. The gasis then delivered vto astorage tank from which it may be removed for anypurpose, an example of which is for carbonating beverages.

VThe physical changes which occur in the operation of this apparatuswill now be described lin greater detail. One end of the prim arycondenser'coil extends into the vapor space, and' since it is open itpermits the CO2 95 to enter it as the solid CO2 in the containersublimes. The bulk of this coil is located atv the bottom ofthecontainer where it is lin contact with and subjected'to thecoolingaction of the solid CO2. During sublimation ,100

heat is supplied to the solid CO2 through heat contacting wall of thecontainer, the pressure rises and liquefaction of the CO2 in the coiloccurs. This liquid is immediately expelled from the condenser coil intoa receiving coil located outside of the container where the liquid ismomentarily held in readivness for use. T he pressure-,temperaturerelation for sublimation in the containerand hquefaction in the prlmarycondenser coil 1s i then 150 lbs. pressure absolute 'and a liquid isonly by temperatureof minus 40 F.A .l

The assumption of 150 pounds of pressure way of example since thispressure may be varied'between wide limits, depending upon theadjustment of the blow-off relief valve 34,01 the adjustment of a reliefwith this apparatus, liquid carbon dioxide will of course form incontainer l-at the same time that solid carbon dioxidel is present, to-`gether with carbon dioxide gas. In otlierr words, Whenthe triple pointtemperatureand pressure conditions for carbon dioxide `are attainedwithin the container l1, carbon dioxide will be present in gaseous,liquid and solid form. This fact does not, however, prevent theapparatus from operating, nor prei vent the formation of liquid carbondioxide in the liquid'coil 10 andin the other parts of the system asdisclosed. 4

It is well known and has long been observed that carbon dioxide inprocess of liquefaction behaves diderently than other well known gasessuch as for example ammonia. Ammonia during its processof liquefactioncannot be cooled to a lower temperature than that of the water overflowfrom the cooling con-l denser, while' carbon dioxide on the other handmay be sub-cooled below the overflow temperature of the water. It hasbeen observed in many tests that the temperature of carbon dioxide gasin a condenser vduring eondensationvaries considerably and thisvariation 'can be traced to the point of change in state,.that is,wherehthe gas changes into a liquid. This is duexin' a considerablemeasure to the fact that the heat does not readily travel through alayer of carbon dioxide aas or vapor. The insulatinV property of thisgas is high, in fact, much igher than that of air s o that thetemperature of the liquid at the end of condensation, and where thistelnthe into gas.

the container is approximately perat'ure is lowest, is not aiiected bythe higher temperature of the gas within the condenser, although the gasas Well as the liquid,

is at the saine pressure.

This condition becomes more drastic and more apparent and is easilyobserved when solid carbon dioxide sublimes in a pressure vessel. Inthis case there appears'to be an enti-re disruption of the relationshipbetween temperature and pressure. For'instance,the solid carbon dioxideat the bottom of the containcris little inliuenced by the pressurepresent in the same container. The temper'- ature of the solid carbondioxide deviates little from its temperature orv *109 F. regardless of.the vpressure which develops in the con'talner by the sublimation ofthesolid The temperature -o the `liquid must necessarily be regulated abovethe temperature of crystallization which is adjusted by the flow ofliquid out of the container into the liquid receiver. It is necessarilytrue that if the liquid which has collected at the bottom of thecontainer is allowed to remain there in a static condition, it will becooled by the solid carbon dioxide to the point of crystallization andthus solidified.

However, when thisliquid is drawn from the container at a temperatureabove crystallization, it will not `freeze as will readily be apparent.The pressure on the other hanfl which is developed by the continuoussublimation of the enclosed solid carbon dioxide .mounts'steadily tohigher levels. Therefore, temperatures at great variation can beobserved in the container; for instance, which collects near mayapproach the temperature existingon the outside thereof. Atl theapproximate mid-distance between the top and the bottoni of thecontainer, the temperature will be found considerably lower; at thevbottom where the liquid exists, temperatures of -40Q F. occur, and, atthe same time, the temperature of the metal bottom of the container uponwhich the solid carbon dioxide .rests will be as low as 100 F. Duringall of this time, the pressure in the container will be close to thatcorresponding with lthe temperature of the gas near the top. if thetemperature of the gas near the top of pressure within the container`would be found to be above 700 pounds per square inch.

Here again, it seems apparent that'the in-y the gas the top of thecontainer.

In other words..

60 F., uw

sulating property of the gas prevents even temperature equalization ofthe gaseous body within the container.

Experiments carried on by competent physicists have shown that thevolume of solid carbon dioxide limation at the rate of .085% Aper 1 F.increases in temperature.

increases during sub- In this respect, solid carbon dioxide behavesopposlte/to waterice';

the latterLincreSes in volume duringireeing rao ' and decreases 'in`volume' on melting; while the triple point, but

carbon dioxide' decreases in volume while freezing and increases involume when meltsolid field is, therefore, 1 F. per 1,544 poundspressure. Tammann and Bridgeman found that the sublimation of solidcarbon dioxide l can be prevented only at an enormous pressure. Forinstance, 'solid carbon dioxide which has a pressure at the triple pointof 75.14' pounds per square -inch absolute and a correspondingtemperature of -69.86 F. requires an increase in this pressure to 14,220'pounds per square inch with a rise in its temperature to 35.14 F. Thisdemonstrates that the sublimation of solid carbon dioxidecan beprevented only at an enormous increase in pressure.

This explains the increase in pressure Within they container during thesublimation of solid carbon dioxide to above 700 pounds per square inchwhen enclosed in -a pressure vessel, while the liquid temperature nearthe bottom may be as low as 40 F. with a still much lower temperature atthe bottom where solid carbon dioxide is in direct contactwith the metalofthe container.

The equilibrium condition for the fluid phases of solid carbondioxide'shows that the pressure in the container would still climb muchhigher if none of the enclosed carbon .dioxide is withdrawn. Hence, inpractice, the apparatus is provided with a safety disc proportioned tobreak at 1,20() pounds per square' inch, so that the Vcontainer will notbe subjected to dangerous `pressure conditions. 1

Thevliquid is now available ,for refrigerating requirements which isaccomplished .by allowing it to "aporize in cooling coils or v'otherheat absorbmg bodies. During this va-` porization the. heat absorbed ina refrigerator, for example, is then equivalent to all of the heatcarried by the cold liquid out of the solidl CO2 container. Thus. ingiving up its low temperature heat while doing refrigeratingwork, or,-`in other words byA absorbing heat from t e refrigerator space as well asthe goods placed therein the liquid completely vaporizes and finallyitsyapor bccomes super-heated. This super-heated vapor is then returnedto the 'solid CO2 container through a secondary condenser coil woundaround the outside of the container.

in the container thefvapor in the secondaryv condenser coil is cooledand finally recondensed.v Hence the heat lnecessary to provducesublimation of the solid CO2 is the identical quantityof heat absorbedin the refrigerator during the vaporiation -of'the liquid and thesuper-heating of the vapor. Theoretically, therefore, the heat exchangebetween the solid carbon dioxide in the container and the heat in therefrigerator is 100%; it being understood that heat losses aresubstantially eliminated by adequate insulation.

However, it has been found in practice that there isda deficiency invheat which is carried back from the refrigerator to the solid CO2 andthat by reason of such deficiency there developes a shortage in vaporsublimation and therefore of liquefaction. This deficiency is obviouslysmall and can easily be supplied by heat from some external source. Inthe system of this invention a small electrical heating elementautomatically controlled by a thermostat-ic switch placed inside oftherefrigerator is employed. Due to the insufficiency of heat carried intothe solid carbon dioxide the solid carbon dioxide docs not sublime insuicient quantity so that y the temperature in the refrigerator spacewill .slowly rise. As soon as the upper predetermined temperature limithas been reached in the refrigerator the thermostatic switch`automatically closesy to complete the circuit to the electrical heatingelement. The heat generated by this heating element within .the solidCO2 container causes a greater quantity of solidl CO2 to sublime, and asa `consequence provides more liquid to increase refrigeration and tolower the temperature in the refrigerator. At a predetermined lower.temperature limit in the refrigerator the thermostatic switchautomatically opens and the process then continues as a closed cycle.

There are other objects of this invention as will appear from thefollowing detailed disclosure.

Referring to the drawing', the 'container for the solid carbon dioxideis shown at 1 havin a movable cover 2 which is held in sealing relationwith thecontaine'r by any suitable clamping means 3. This container issupported within a heat insulating cabinet 4 provided with a removablecover 5. Within the container 1 and spaced a suitable distance from thebottom thereof is a transverse perforated wall 6 on .which one or moreblocks 7 of solid carbon dioxide are supported. The volume of thecontainer 1 with respect to the volume of solid placed therein must besuch that the solid may vaporize and lgenerate pressure. Openingintocontainer 1 is a pipe f 10 into oneend of which is connected thepipe During the heat exchange with the solid CO2 8. The other end ofthis condenser' coil is connected by pipe 11 to the liquid coil 12within the refrigerator 13,-which may be fa manner, or may itself vbemade of heat insulating material such asrefrigerator cabinets and thelike.

The other end of liquid coil 12 is connected by pipe 16 to a oat valve17 of any well known construction. The outlet of the float valve isconnected by pipe 18 to a header 19. The float valve is arranged withrespect to the header 19 so that a suitable body of liquid carbondioxide will be maintained therein as indicated in the drawing. At 21isanother header which is connected to the header 19 by a plurality ofparallel pipes 20. v

' Near the top of header 21 is provided a pipe connection 22 leading toa thermostatic control valve 23. This thermostatic control valve may beof oany well known type and is placed withinthe, refrigerator so as tobe subject to thev temperature conditions therein. It is, of course,adjusted so as to prevent the temperature within the cabinet fallingbelow the predetermined value and acts to Shut off the flow of gas whenthat value is attained. The outlet of the thermostatic control valve 23irs-connected by pipe 24 which extends to a secondary condenser coil 25which encircles the container- 1 in heat exchange relation. The outletof coil 25' is connected by a pipe 26 to a cooling coil 27. This coolingcoil 27 is within a space 28 formed by the glass'wall 29 and the rearwall 30. The space 28 provides, 33

.for example, refrigerated display cabinet such as used in storesselling perishable products. This cabinet is provided with a suitabledoor 31 by means of which access to the interior may be had.

Suitably mounted within the container 1 is an electrical heating coil 40of any suitable constructon. At 41 is a thermostatic switch /which isexposed to the temperature conditions within the refrigerator 13. 43repre.- sents any suitable current source connected to the heaterelement and the thermostatic switch by wires 42. Itis, of course,apparent that this invention is not limited to an electrical heatingmeans for supplying external heat since other well knownforms of heatingdevices may be used.

The outlet of coil 27 is connected by pipe 32 to a gas storage receivingtank 33.- This tank is provided with a suitable release valve v. cover 2and clamp 3. The insulating cabinet' 34 for permitting the escape of thegas vif the pressure therein tends to build abovela predetermined value.This tank is also provided with a delivery pipe 35 and control valve 36by means of `*which the gas may be deliv ered for any'use, suchas forexample the carbonating of beverages.

The operation of this apparatus is as follows: A suitable quantity ofsolid carbon dioxide in the form of blocks 7 is placedwithin thecontainer 1, which is sealed by means o 4 is then closed by means of thecover 5. i As the solid carbon dioxide sublimates the gas by the lformedwithinthe free space the container then flows down through pipe 8 ofcooling coil 10 where it is cooled suiiiciently to liquefy. The liquidthen iiows through pipe 11 to f the refrigerators and the articlestherein, as

does the relatively cold gas flowing through the pipes 20. This flow ofgas is controlled gas then condenser coil 25 where it is cooled andagain liquefied, giving up its heat to effect further gasification ofthe solid carbon dioxide within the containeril. The liquid, or themixho ture of liquid and vapor then flows through pipe 26 to thecoolingqoil .27 withinthe second refrigerating space 28 where it absorbsheat therefrom, as' well as from thev articles therein.v The gas is thendelivered through pipe 32 to the storage receiving tank tion that thisprocess is a very economical one.l With the apparatus disclosed and the'method employed the very cold solid carbon dioxide is transformed intoliquid and gaseous phases and employed to do useful work in absorbingheat from articleslto be cooled. Furthermore, the heat absorbed isemployed to leect further yvaporization of the solid, and finally thestill relatively cool gas at a thermostatic control valve 23. Theflowsfrom pipe 24 to thesecondary.

lt will be apparent from the above descrip-Sv super-atmospheric pressureis available for` other uses.

Any deficiency in this heat exchange is 'Y then supplied by heat from anoutside source so controlled by the thermostatic switch that onlysuchheat velop is made up side source.A i

The approximate temperatures and pressures involved will be given in anillustrative sense and with no intention of restricting the scope of theinvention. The solid carbon dioxide is at approximately minus 109"4 F.When it is permitted to vaporize within the from any convenient outfdeficiency as may actually de" container 1 the. gas pressure thereinrises to approximately 150 pounds pressure per square inch. This gas atthis pressure vand temperature when it flows throughthe primarycondensing coil 10 in heat exchange relation with the soild is undersuch conditions f that it liquefies. `The liquid flowing from the coilsthrough pipe 11 intoliquid coil 12 is at approximately minus 40 F., andl150 lbs.

pressure. The gas flowing from the gas pipes 20 through pipes 22 and 24is at approximatel minus 10 F. and 115-lbs. pressure. After flowingthrough the cooling coils 25 the gas vis at approximately minus 50 F.and 100 lbs. pressure. After 1leaving the coil 27 the gas is at fromminus 10 ,to 0o F. and at approximately 80 lbs. pressure. It isvstoredwithin the gas storage tank at approximately 80 lbs. pressure.

Among the many uses to which this still relatively cool gas atsuper-atmospheric pressure may be applied is that of vcarbonatingbeverages.- Beverages are usually carbonated at about lbs. pressure persquare inch, so that the gas in the storage tank is at once availablefor this purpose.

The check valve 9 is provided in the -pipe 8 so that when the container1 is open for the admission of further solid carbon dioxide thepressures within the various pipes and coils w1ll not escape into theatmosphere as it would do if no check valve were provided.

From the foregoing disclosure it will be apparent that this inventioninvolves Acert-ain .principles of construction and operation which maybe readily embodied in other apparatus and methods as will be apparentto those skilled in the art. I do not, therefore, desire to he strictlylimitedby the disclosure, either inthe drawing or spec1ficat1on,

-as given for the-purpose of illustrating my invention, but ratherto thescope of the appended claims. U y

What I seek to sec re by Unlted States Letters Patent is:

l1. In a refrigerating apparatus, the combination comprising tworefrigerators, re-

frigerating coils in said refrigerators, and means connected to saidcoils for recelvlng solid carbon dioxide from which liquid carbondioxide refrigerant is delivered to the coils of said refrigerators.

2. In a refrigerating apparatus, the combination comprising a containerfor solid,

carbon dioxide, a refrigerating cabinet having a cooling coil therein,connections between the container and the cooling coil, a coilsurrounding said container and connected to the coolingcoil of therefrigerating cabinet, a second refrigerating cabinet havin a coolingcoil therein, and connections etween the cooling coil in the secondrefrigerating cabinet and the cooling coil surrounding the container.type described, the combination comprising a container for solid carbondioxide, a cooling coil in heat exchange relation' with said containerand 'opening into the interior thereof, a refrigerating cabinet, acooling coil in.'

. said cabinet connected to said rst cooling coil, another coilencircling the container and connected to the cooling coil within therefrig- 4erating cabinet, a second refrigerating cabinet having acooling coil' therein, and con- .erating cabinet frigerating .cabinethaving a coll and a.l gas vcooling' coil therein, connections 3. In arefrigerating apparatus of they nections between the cooling coil in thesecond refrigerating cabinet and the circling` said container.

4. In a refrigerating apparatus of the type described, the combinationcomprising a container for solid carbon dioxidea. cooling coil in heatexchangev relation with said container and opening into the interiorthereof, a refrigerating-cabinet, a cooling coil in said cabinetconnected to said irst cooling coil, another coilencircl ing thecontainer and connected to thecooling coil within the refrigeratingcabinet, a second refrigerating cabinet having a cooling coil therein,connections between the cooling coil in the second refrigerating cabinetandthe cooling coil encircling said container, and means within saidfirst cooling cabinet'in the connections between the cooling coiltherein and the cooling coil encircling said container for maintaining apredetermined temperature 4condition Within that cabinet.-

5. type described, the combination 'comprising a container for solidcarbon dioxide, a cooling coilin heat exchange relation with saidcontainer and opening into the interior thereof, a refrigeratingcabinet, a cooling coil in said cabinet connected to said first coolingcoil, another coil encircling` the container and connected to thecooling coil within the refrigerating cabinet, a second refrigeratingcabinet having a cooling coil therein, connections between the coolingcoil in the second refrigand thecooling coil encircling said container,and gaseous carbon dioxide storing means connected to the cooling coilwithin 'the second refrigerating cabinet.

6. Ina refrigerati-ing apparatus of the type described, the combinationcomprising a refrigerating cabinet having a liquid cooling coil and agas cooling coil therein, connections between said coils including aiioat valve for controlling the delivery of liquid from the liquid' coilto the gas coil, and means fordelivering liquid carbon dioxide tocoolingcoil enthe liquid coil.

7. In a refrigerating apparatus of the type described, the combinationcomprising a reliquid cooling between said coils including afloat valvefor controlling the delivery of liquid from the liquid coil to the gascoil, andv means for transforming solid carbon dioxide into liquidcarbon dioxide connected to the' liquid coil of the refrigerator. Y i 8.In a refrigerating apparatus of the type described, the combinationcomprising a container for receiving solid. carbon dioxide, a condensingcoil in heat'exchange relation In a refrigerating apparatus ofthe withsaid container Aand opening therein, a

refrigerator having a liquid coil and agas coil thereinconnected'together, a vconnection between the condensing co1l and theliquid coil, a cooling coil in heat exchange relation with saidcontainer, a connection between that cooling coil and the gas coil ofthe refrigerator, a second refrigerator having a cooling coil therein,and a l connection between the cooling coil of the second refrigeratorand the cooling coil in heat exchange relation with the container.

9. In a refrigerating apparatus of the type described, the combinationcomprising a container for receiving solid carbon dioxide, a condensingcoil in heat exchange relation with said container and opening therein,a rel frigerator having a liquid coil and a gas coil therein connectedtogether, a connection between the condensing coil and the liquid coil,a cooling coil in heat exchange relation with said container, aconnection between that cooling coil and the gas coil of therefrigerator, a secondvrefrigerator having a cooling coil therein, a.connection between the cooling cooling coil coil of the secondrefrigerator and the cooling coil in heat exchange relation with thecontainer, and means in the connection between the liquid coil and thegas'coil of thel refrigerator for maintaining a predetermined quantityof liquid in the gas coil.

l 10. In a refrigerating apparatus of the type described, thecombination comprising a container for receiving solid carbon dioxide, acondensing coil in heat exchange relation with said container andopening therein, a refrigerator having a liquid coil and a gas coiltherein connected together, a connection between the condensing coil andthe liquid circulating the gaseous carbon dioxide in heat,

exchange relationwith the solid carbon dioxide to liquefy it,circulating the liquid cari bon dioxide within aspace to berefrigerated,

transforming the liquid carbon dioxide to gaseous carbon dioxide withinthat space, circulating the gaseous carbon dioxide in lheat exchangerelation with solid carbon dioxide to cool it, and circulating thecooled carbon dioxide gas in heat exchange relation with therefrigerating space.

12. In a-refrigerating method of the type described, thelstepsofsublimating solid carbon dioxide to form gaseous carbon dioxide,circulatingthe gaseous carbon dioxide in heat exchange relation with thesolid carbon dioxide to liquefy it, circulating the liquid carbondioxide within a space to be refrigerated, transformingthe liquid carbondioxide to gaseous carbon dioxide within that space, circulating thegaseous carbon dioxide'in heat exchange relation withsolid carbondioxide to cool it, circulating the cooled carbon dioxide gas in heatexchange relation with the refrigerating space, and storing the carbondioxide gas atvsuper-atmospheric pressure.

18. A refrigerating cycle employing solid carbon dioxide comprisingtransforming solid carbon dioxide into gaseous carbon dioxide,

circulating the gaseous carbon dioxide in heat exchange relation to theremaining solid c arbon dioxide to liquefy it, circulating the liquidcarbon dioxide in heat exchange'relation with articles to be cooled,transforming the liquid carbon dioxide into gaseous carbou dioxide andcirculating the gaseous carbon dioxide in heat exchange relation withartlcles to be cooled,circulating the relatively warm gaseous carbondioxide in heat exchange relation with the solid carbon dioxide to coolVthe gas and effect further vaporization of the solid, and circulatingthe cooled carbon dioxide gas in heat exchange relation with articles tobe cooled.

14. A refrigerating cycle employing solid carbon dioxide comprisingltransforming solid carbon dioxide into gaseous-carbon dioxide,circulating the gaseous carbon dioxide in heat exchange relation to theremaining solid carbon dioxide to liquefy it, circulating vthe liquidcarbon dioxide in heat exchange relation with articles to be cooled,transformingv the liquid carbon dioxide into gaseous carbon dioxide andcirculating the gaseous carbon dioxide in heat exchange relation witharticles to be cooled, circulating the relatively warm gaseous carbondioxide in heat exchange relation with the solid carbon dioxide to coolthe gas and effect further vapori'zation of the solid, circulating thecooled carbon dioxide gas in heat exchange relation with articles to becooled,l and `using theA carbon dioxide gas to carbonate beverages.

.15. In a refrigerating apparatus, the combination comprising acontainer for solid carbon dioxide, a refrigerating cabinet having acooling coil therein, connections between the' container and the coolingcoil, a coil surrounding said container and connected to the coolingcoil of the refrigerating cabinet, a second'refrigerating cabinet havinga cooling coil therein, connections between the cooling coil in thesecond refrigerating cabinet and the cooling coil surrounding the con,-tainer, and means for supplying external heat to the container. y

16. In a refrigerating apparatus, the combination comprising a containerfor solid carbon dioxide, a refrigerating cabinet having a cooling coiltherein, connections between the container and the cooling coil, a

coil surrounding said container and con` y automatically energizing it.

17. In a refrigerating apparatus, the combination comprising a containerfor solid carbon dioxide, a refrigerating cabinet having a cooling coiltherein, connections between the container and the cooling coil, a coilsurrounding said container and connected to the cooling coil of therefrigerating cabinet, a second refrigerating cabinet having a coolingcoil therein, connections between the cooling coil in the secondrefrigerating dioxide to liquid carbon dioxide, comprising a closedvchamber and a condensing coil with-A in said chamber, said condensingcoil being open to the interior of the chamber.

In testimony whereof I have hereunto set my hand on this 10thday ofOctober, A. 1)

JUSTUS C. GOOSMANN.

cabinet and the cooling coil surrounding the v container, an electricalheating device withinv said container, a thermostatic switch within therst refrigerating cabinet and connections between the electrical heatingdevice n and the thermostatic switch whereby the electrical heatingdevice is energized upon the 'increase sublimation.

development of predetermined temperature conditions within therefrigeratin cabinet.

18. In a refrigerating method o the type described, the steps ofsublimating solid carbon dioxide to form gaseous carbon dioxide,

circulating the gaseous carbon dioxide in heat lexchange relation Withthe solid carbon dioxide .to liquefy it, circulating the liquid carbondioxide within a space to be refrigerated,

transforming the liquid carbon dioxide toA gaseous carbon dioxide withinthat space,

circulating the4 gaseous carbon dioxide in heat exchange relation withsolid carbon dioxide to coolit, circulating the cooled carbon dioxidegas in heat exchange relation with the refrigerating space, andsupplying external heat-to the solid carbon dioxide to 19.v Ina-refrigerating method of the type described, the steps of sublimatingsolid carbon dioxide to form gaseous carbon dioxide, circulating thegaseous carbon dioxide in heat exchange relation with the solid carbondioxide to liquefy it, circulatin the liquid carbon dioxide within aspace toe refrigerated, transforming the liquid carbon dioxide togaseous carbon dioxide Within that space, circulating the gaseous carbondioxide in heat exchange relation with solid-carbon dioxide to cool 1t,circulating the cooled carbon dioxide gas in heat exchange relation withthe refrigerating space, and supplying external heat under control ofthe temperature con-.-

ditions in the lirst refrigerating space to lincrease the sublimation ofthe solid carbon d1ox1de.

20. A converter for changing solid carbon

